Which has greater linear speed, a horse near the outside rail of a
merry-go-round or a horse near the inside rail?
outside horse
inside horse
both the same
Which has greater angular speed, a horse near the outside rail of a
merry-go-round or a horse near the inside rail?
outside horse
inside horse
both the same
Ralph told me that he is confused about radians. In the textbook, the
angle in radians is defined as s/r. Both s and r
are lengths, so
they should both have units of meters. These units should cancel out
in the ratio s/r. This should leave us with no units. It seems that
the units of radians just appear from nothing. Could you help Ralph understand
radians better?
If the velocity of an object changes direction but its speed
remains the same, it
has or
has not
been accelerated.
The reason the moon does not fall into Earth is that
the gravitational pull of the Earth on
the moon is weak,
the moon has a sufficiently
large orbital
speed,
the gravitational pull of other planets
keeps the moon up,
the moon has less mass than Earth, or
none of the above.
Ralph is confused about centripetal and centrifugal forces.
When he is in a car which is turning to the right, he feels a force
pushing him to the left. But the textbook says that the actual force
is pushing him to the right. Can you explain this to him? What is
he actually feeling during the turn?